Composite magnetic sealing material and electronic circuit package using the same as mold material

ABSTRACT

Disclosed herein is a composite magnetic sealing material includes a resin material and a filler blended in the resin material in a blend ratio of 50 vol. % or more and 85 vol. % or less. The filler includes a first magnetic filler containing Fe and 32 wt. % or more and 39 wt. % or less of a metal material composed mainly of Ni, the first magnetic filler having a first grain size distribution, and a second magnetic filler having a second grain size distribution different from the first grain size distribution.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a composite magnetic sealing materialand an electronic circuit package using the composite magnetic materialas a mold material and, more particularly to a composite magneticsealing material suitably used as a mold material for an electroniccircuit package and an electronic circuit package using the compositemagnetic sealing material as a mold material.

Description of Related Art

In recent years, an electronic device such as a smartphone is equippedwith a high-performance radio communication circuit and ahigh-performance digital chip, and an operating frequency of asemiconductor IC used therein tends to increase. Further, adoption of anSIP (System-In Package) having a 2.5D or 3D structure, in which aplurality of semiconductor ICs are connected by a shortest wiring, isaccelerated, and modularization of a power supply system is expected toaccelerate. Further, an electronic circuit module having a large numberof modulated electronic components (collective term of components, suchas passive components (an inductor, a capacitor, a resistor, a filter,etc.), active components (a transistor, a diode, etc.), integratedcircuit components (an semiconductor IC, etc.) and other componentsrequired for electronic circuit configuration) is expected to becomemore and more popular, and an electronic circuit package which is acollective term for the above SIP, electronic circuit module, and thelike tends to be mounted in high density along with sophistication,miniaturization, and thinning of an electronic device such as asmartphone. However, this tendency poses a problem of malfunction andradio disturbance due to noise. The problem of malfunction and radiodisturbance is difficult to be solved by conventional noisecountermeasure techniques. Thus, recently, self-shielding of theelectronic circuit package has become accelerated, and anelectromagnetic shielding using a conductive paste or a plating orsputtering method has been proposed and put into practical use, andhigher shielding characteristics are required in the future.

To achieve this, recently, there are proposed electronic circuitpackages in which a molding material itself has magnetic shieldingcharacteristics. For example, Japanese Patent Application Laid-Open No.H10-64714 discloses a composite magnetic sealing material added withsoft magnetic powder having an oxide film as a molding material forelectronic circuit package.

However, conventional composite magnetic sealing materials have adrawback in that it has a large thermal expansion coefficient. Thus, amismatch occurs between a composite magnetic sealing material and apackage substrate or electronic components in terms of the thermalexpansion coefficient. As a result, an aggregated substrate having astrip shape after molding may be greatly warped, or there may occur awarp large enough to cause a problem with connectivity of an electroniccircuit package in a diced state in mounting reflow. This phenomenonwill be described in detail below.

In recent years, various structures have been proposed for and actuallyput into practical use as a semiconductor package or an electroniccomponent module, and, currently, there is generally adopted a structurein which electronic components such as semiconductor ICs are mounted onan organic multilayer substrate, followed by molding of the upperportion and periphery of the electronic component package by a resinsealing material. A semiconductor package or electronic component modulehaving such a structure is molded as an aggregated substrate, followedby dicing.

In this structure, an organic multilayer substrate and a resin sealingmaterial having different physical properties constitute a so-calledbimetal, so that a warp may occur due to the difference between thermalexpansion coefficients, glass transition, or curing shrinkage of amolding material. To suppress the warp, it is necessary to make thephysical properties such as thermal expansion coefficients coincide witheach other as much as possible. In recent years, an organic multilayersubstrate used for a semiconductor package or an electronic circuitmodule is getting thinner and thinner and is increasing in the number oflayers thereof to meet requirements for height reduction. In order torealize high rigidity and low thermal expansion for ensuring goodhandleability of a thin substrate while achieving the thicknessreduction and multilayer structure, use of a substrate material having ahigh glass transition temperature, addition of a filler having a smallthermal expansion coefficient to a substrate material, or use of glasscloth having a smaller thermal expansion coefficient is a commonpractice at present.

On the other hand, the difference in physical properties betweensemiconductor ICs and electronic components mounted on a substrate and amolding material also generates a stress, causing various problems suchas interfacial delamination of the molding material and crack of theelectronic components or molding material. Incidentally, silicon is usedas the semiconductor ICs. The thermal expansion coefficient of siliconis 3.5 ppm/° C., and that of a baked chip component such as a ceramiccapacitor or an inductor is about 10 ppm/° C.

Thus, the molding material is also required to have a small thermalexpansion coefficient, and some commercially-available materials have athermal expansion coefficient below 10 ppm/° C. As a method for reducingthe thermal expansion coefficient of the molding material, adopting anepoxy resin having a small thermal expansion coefficient, as well as,blending fused silica having a very small thermal expansion coefficientof 0.5 ppm/° C. in a sealing resin at a high filling rate can be taken.

General magnetic materials have a high thermal expansion coefficient.Thus, as described in Japanese Patent Application Laid-Open No.H10-64714, the composite magnetic sealing material obtained by addinggeneral soft magnetic powder to a mold resin cannot achieve a targetsmall thermal expansion coefficient.

SUMMARY

It is therefore an object of the present invention to provide acomposite magnetic shield material having a low thermal expansioncoefficient.

Another object of the present invention is to provide an electroniccircuit package using the composite magnetic shield material having alow thermal expansion coefficient as a mold material.

A composite magnetic sealing material according to the present inventionincludes a resin material and a filler blended in the resin material ina blend ratio of 50 vol. % to 85 vol. %. The filler includes a firstmagnetic filler containing a 32 wt. % to 39 wt. % of metal materialcomposed mainly of Ni in Fe and having a first grain size distributionand a second magnetic filler having a second grain size distributiondifferent from the first grain size distribution.

According to the present invention, by using the first magnetic fillerhaving a small thermal expansion coefficient, the thermal expansioncoefficient of the composite magnetic sealing material can be reduced.In addition, by using the second magnetic filler having a second grainsize distribution different from the first grain size distribution, amagnetic material can be packed at a higher density. Thus, when thecomposite magnetic sealing material according to the present inventionis used as a mold material for an electronic circuit package, it ispossible to reduce the warp of the substrate and the mold package and toprevent interfacial delamination among the mold material, substrate, andmounted components (ICs, passive components, and the like) and crack ofthe mold material due to mismatch of the thermal expansion coefficient,while ensuring high magnetic characteristics.

In the present invention, the metal material may further contain 0.1 wt.% or more and 5 wt. % or less of Co relative to the total weight of thefirst magnetic filler. This enables a further reduction in the thermalexpansion coefficient of the composite magnetic sealing material.

In the present invention, the median diameter (D50) of the firstmagnetic filler is preferably larger than the median diameter (D50) ofthe second magnetic filler. This allows the thermal expansioncoefficient to be sufficiently reduced while ensuring high magneticcharacteristics.

In the present invention, the second magnetic filler preferably containsat least one selected from the group consisting of Fe, an Fe—Co basedalloy, an Fe—Ni based alloy, an Fe—Al based alloy, an Fe—Si based alloy,an Ni—Zn based spinel ferrite, an Mn—Zn based spinel ferrite, anNi—Cu—Zn based spinel ferrite, an Mg based spinel ferrite, and anyttrium-iron based garnet ferrite. This is because the above magneticmaterials each have high magnetic characteristics. Alternatively, thesecond magnetic filler may have substantially the same composition asthat of the first magnetic filler.

In the present invention, the filler may further include a non-magneticfiller. This enables a further reduction in the thermal expansioncoefficient of the composite magnetic sealing material. In this case,the ratio of the amount of the non-magnetic filler relative to the sumof the amounts of the magnetic filler and the non-magnetic filler ispreferably 1 vol. % or more and 30 vol. % or less. This enables afurther reduction in the thermal expansion coefficient of the compositemagnetic sealing material while ensuring sufficient magneticcharacteristics. In this case, the non-magnetic filler preferablycontains at least one material selected from the group consisting ofSiO₂, a low thermal expansion crystallized glass (lithiumaluminosilicate based crystallized glass), ZrW₂O₈, (ZrO)₂P₂O₇,KZr₂(PO₄)₃, or Zr₂(WO₄) (PO₄)₂. These materials have a very small ornegative thermal expansion coefficient, thus enabling a furtherreduction in the thermal expansion coefficient of the composite magneticsealing material.

In the present invention, the first and second magnetic fillerspreferably have a substantially spherical shape. This enables anincrease in the ratio of the first and second magnetic fillers to thecomposite magnetic sealing material.

In the present invention, the surface of the first and second magneticfillers is preferably insulatively coated, and the film thickness of theinsulating coating is preferably 10 nm or more. With this configuration,the volume resistivity of the composite magnetic sealing material can beincreased to, e.g., 10¹⁰ Ωcm or more, making it possible to ensureinsulating performance required for a molding material for an electroniccircuit package.

In the present invention, the resin material is preferably athermosetting resin material, and the thermosetting resin materialpreferably contains at least one material selected from the groupconsisting of an epoxy resin, a phenol resin, a urethane resin, asilicone resin, or an imide resin.

As described above, the composite magnetic sealing material according tothe present invention has a small thermal expansion coefficient and highmagnetic characteristics, so that when it is used as a mold material foran electronic circuit package, it is possible to prevent the warp of thesubstrate, interfacial delamination of the mold material, crack of themold material, and the like while ensuring a high magnetic shieldeffect.

An electronic circuit package according to the present inventionincludes a substrate, electronic components mounted on the surface ofthe substrate, and a magnetic mold resin covering the surface of thesubstrate so as to embed therein the electronic components. The magneticmold resin includes a resin material and a filler blended in the resinmaterial in a blend ratio of 50 vol. % to 85 vol. %. The filler includesa first magnetic filler containing a 32 wt. % to 39 wt. % of metalmaterial composed mainly of Ni in Fe and having a first grain sizedistribution and a second magnetic filler having a second grain sizedistribution different from the first grain size distribution.

According to the present invention, by using the first magnetic fillerhaving a small thermal expansion coefficient, the thermal expansioncoefficient of the magnetic mold resin made of a composite magneticsealing material can be reduced. In addition, the magnetic mold resinfurther includes the second magnetic filler having a grain sizedistribution different from that of the first magnetic filler, so that amagnetic material can be packed at a higher density. Thus, it ispossible to prevent the warp of the substrate, interfacial delaminationof the mold material, crack of the mold material, and the like whileensuring a high magnetic shield effect.

In the present invention, the surface resistance value of the magneticmold resin is preferably 10⁶Ω or more. With this configuration, evenwhen the magnetic mold resin is covered with a metal film, an eddycurrent to be generated when electromagnetic wave noise enters a metalfilm hardly flows into the mold resin, making it possible to preventdeterioration in the magnetic characteristics of the magnetic mold resindue to inflow of the eddy current.

It is preferable that the electronic circuit package further includes ametal film covering the magnetic mold resin, wherein the metal film isconnected to a power supply pattern provided in the substrate. With thisconfiguration, a composite shielding structure having both anelectromagnetic shielding function and a magnetic shielding function canbe obtained.

Preferably, in the present invention, the metal film is mainly composedof at least one metal selected from a group consisting of Au, Ag, Cu,and Al, and more preferably, the surface of the metal film is coveredwith an antioxidant film. In the present invention, it is preferablethat the power supply pattern is exposed to a side surface of thesubstrate and that the metal film contacts the exposed power supplypattern. With this configuration, it is possible to easily and reliablyconnect the metal film to the power supply pattern.

The electronic circuit package according to the present invention mayfurther include a soft magnetic metal film that covers the magnetic moldresin. With this configuration, a double magnetic shield structure canbe attained, allowing higher magnetic characteristics to be obtained.

The electronic circuit package according to the present invention may beconnected to a power supply pattern mounted on the substrate and mayfurther includes a soft magnetic metal film that covers the magneticmold resin. With this configuration, it is possible to obtain acomposite shield structure having both an electromagnetic shieldfunction and a magnetic shield function and to obtain higher magneticcharacteristics. In this case, the soft magnetic metal film ispreferably made of Fe or an Fe—Ni based alloy. With this configuration,high magnetic characteristics and high conductivity can be imparted tothe soft magnetic metal film itself.

As described above, the electronic circuit package according to thepresent invention uses a magnetic mold resin having a small thermalexpansion coefficient and high magnetic characteristics as a mold resin,so that it is possible to reduce the warp of the substrate and thepackage and to prevent interfacial delamination of the mold material andcrack of the mold material due to mismatch of the thermal expansioncoefficient, while ensuring high magnetic shielding characteristics.

BRIEF DESCRIPTION OF THE DRAWINGS

The above features and advantages of the present invention will be moreapparent from the following description of certain preferred embodimentstaken in conjunction with the accompanying drawings, in which:

FIG. 1 is a cross-sectional view illustrating a configuration of anelectronic circuit package according to a first embodiment of thepresent invention;

FIG. 2 is a cross-sectional view illustrating a configuration of anelectronic circuit package according to a first modification of thefirst embodiment;

FIGS. 3 to 5 are process views for explaining a manufacturing method forthe electronic circuit package shown in FIG. 1;

FIG. 6 is a schematic view for explaining a configuration of a compositemagnetic sealing material;

FIG. 7 is a graph illustrating the relationship between the Ni ratio ofthe first magnetic filler and the thermal expansion coefficient and themagnetic permeability of the composite magnetic sealing material;

FIG. 8 is a graph illustrating the relationship between the Ni ratio ofthe first magnetic filler and the thermal expansion coefficient of thecomposite magnetic sealing material;

FIG. 9 is a graph illustrating the relationship between the Ni ratio ofthe first magnetic filler and the magnetic permeability of the compositemagnetic sealing material;

FIG. 10 is a graph illustrating the relationship between the Co ratio ofthe first magnetic filler and the thermal expansion coefficient andmagnetic permeability of the composite magnetic sealing material;

FIG. 11 is a graph illustrating the relationship between the additiveratio of the non-magnetic filler and the thermal expansion coefficientof the composite magnetic sealing material;

FIG. 12 is a graph illustrating the relationship between thepresence/absence of the insulating coat formed on the surface of thefirst magnetic filler and volume resistivity;

FIG. 13 is a graph illustrating the relationship between the filmthickness of the insulating coat formed on the surface of the firstmagnetic filler and volume resistivity;

FIG. 14 is a graph illustrating the relationship between volumeresistivity of the first magnetic filler and that of the compositemagnetic sealing material;

FIG. 15 is a cross-sectional view illustrating a configuration of anelectronic circuit package according to a second embodiment of thepresent invention;

FIGS. 16 to 18 are process views for explaining a manufacturing methodfor the electronic circuit package shown in FIG. 15;

FIG. 19 is a cross-sectional view illustrating a configuration of anelectronic circuit package according to a third embodiment of thepresent invention;

FIG. 20 is a cross-sectional view illustrating a configuration of anelectronic circuit package according to a first modification of thethird embodiment;

FIG. 21 is a cross-sectional view illustrating a configuration of anelectronic circuit package according to a second modification of thethird embodiment;

FIG. 22 is a cross-sectional view illustrating a configuration of anelectronic circuit package according to a third modification of thethird embodiment;

FIG. 23 is a cross-sectional view illustrating a configuration of anelectronic circuit package according to a fourth modification of thethird embodiment;

FIG. 24 is a graph illustrating noise attenuation in the electroniccircuit package shown in FIG. 19;

FIGS. 25 to 27 are graphs each illustrating the relationship between thefilm thickness of the metal film included in the electronic circuitpackage shown in FIG. 19 and noise attenuation;

FIG. 28 is graphs illustrating the warp amount of the substrate duringtemperature rising and that during temperature dropping in theelectronic circuit packages shown in FIGS. 1 and 19;

FIG. 29 is graphs illustrating the warp amount of the substrate duringtemperature rising and that during temperature dropping in theelectronic circuit packages of a comparative example;

FIG. 30 is a cross-sectional view illustrating a configuration of anelectronic circuit package according to a fourth embodiment of thepresent invention;

FIG. 31 is a process view for explaining a manufacturing method for theelectronic circuit package shown in FIG. 30;

FIG. 32 is a process view for explaining a manufacturing method for theelectronic circuit package shown in FIG. 30;

FIGS. 33 and 34 are graphs indicating a grain size distribution of thefirst and second magnetic fillers and the non-magnetic filler;

FIG. 35 is a cross-sectional view illustrating a configuration of anelectronic circuit package according to a fifth embodiment of thepresent invention;

FIG. 36 is a cross-sectional view illustrating a configuration of anelectronic circuit package according to a modification of the fifthembodiment;

FIG. 37 is a cross-sectional view illustrating a configuration of anelectronic circuit package according to a sixth embodiment of thepresent invention;

FIG. 38 is a cross-sectional view illustrating a configuration of anelectronic circuit package according to a modification of the sixthembodiment;

FIG. 39 is a cross-sectional view illustrating a configuration of anelectronic circuit package according to a seventh embodiment of thepresent invention;

FIG. 40 is a cross-sectional view illustrating a configuration of anelectronic circuit package according to a modification of the seventhembodiment; and

FIG. 41 is a cross-sectional view illustrating a configuration of anelectronic circuit package according to an eighth embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Preferred embodiments of the present invention will be explained belowin detail with reference to the accompanying drawings.

First Embodiment

FIG. 1 is a cross-sectional view illustrating a configuration of anelectronic circuit package 11A according to the first embodiment of thepresent invention.

As illustrated in FIG. 1, the electronic circuit package 11A accordingto the present embodiment includes a substrate 20, a plurality ofelectronic components 31 and 32 mounted on the substrate 20, and amagnetic mold resin 40 covering a front surface 21 of the substrate 20so as to embed the electronic components 31 and 32.

Although the type of the electronic circuit package 11A according to thepresent embodiment is not especially limited, examples thereof include ahigh-frequency module handling a high-frequency signal, a power supplymodule performing power supply control, an SIP (System-In-Package)having a 2.5D structure or a 3D structure, and a semiconductor packagefor radio communication or digital circuit. Although only two electroniccomponents 31 and 32 are illustrated in FIG. 1, more electroniccomponents are incorporated actually.

The substrate 20 has a double-sided and multilayer wiring structure inwhich a large number of wirings are embedded therein and may be any typeof substrate including: a thermosetting resin based organic substratesuch as an FR-4, an FR-5, a BT, a cyanate ester substrate, a phenolsubstrate, or an imide substrate; a thermoplastic resin based organicsubstrate such as a liquid crystal polymer; an LTCC substrate; an HTCCsubstrate; and a flexible substrate. In the present embodiment, thesubstrate 20 has a four-layer structure including wiring layers formedon the front surface 21 and a back surface 22 and two wiring layersembedded therein. Land patterns 23 are an internal electrode forconnecting to the electronic components 31 and 32. The land patterns 23and each of the electronic components 31 and 32 are electrically andmechanically connected to each other through a respective solder 24 (ora conductive paste). For example, the electronic component 31 is asemiconductor chip such as a controller, and electronic component 32 isa passive component such as a capacitor or a coil. Some electroniccomponents (e.g., thinned semiconductor chip) may be embedded in thesubstrate 20.

The land patterns 23 are connected to external terminals 26 formed onthe back surface 22 of the substrate 20 through internal wirings 25formed inside the substrate 20. Upon actual use, the electronic circuitpackage 11A is mounted on an unillustrated mother board, and landpatterns on the mother board and the external terminals 26 of theelectronic circuit package 11A are electrically connected. A materialfor a conductor forming the land patterns 23, internal wirings 25, andexternal terminals 26 may be a metal such as copper, silver, gold,nickel, chrome, aluminum, palladium, indium, or a metal alloy thereof ormay be a conductive material using resin or glass as a binder; however,when the substrate 20 is an organic substrate or a flexible substrate,copper or silver is preferably used in terms of cost and conductivity.The above conductive materials may be formed by using various methodssuch as printing, plating, foil lamination, sputtering, vapordeposition, and inkjet.

The magnetic mold resin 40 covers the front surface 21 of the substrate20 so as to embed the electronic components 31 and 32 therein. Themagnetic mold resin 40 is a mold member and serves also as a magneticshielding. In the present embodiment, a side surface 42 of the magneticmold resin 40 and a side surface 27 of the substrate 20 form the sameplane. Although details of the magnetic mold resin 40 will be explainedlater, the magnetic mold resin 40 composed of a composite magneticsealing material having very small thermal expansion coefficient (15ppm/° C. or less for example) compared with a conventional magneticsealing material. The magnetic mold resin 40 contacts the electroniccomponents 31, 32 and land patterns 23, so that the volume resistancethereof needs to be sufficiently large. Specifically, it is desirablethat the volume resistance is equal to or larger than 10¹⁰ Ωcm.

Further, when a distance between an electronic component such as ahigh-frequency inductor and the magnetic mold resin 40 is too small,characteristics thereof such as an inductance value may fluctuate from adesign value. In such a case, the fluctuation of the characteristics canbe reduced by covering a part of or the entire electronic component witha non-magnetic member. FIG. 2 is a cross-sectional view illustrating aconfiguration of an electronic circuit package 11B according to amodification. The electronic circuit package 11B of FIG. 2 differs fromthe electronic circuit package 11A of FIG. 1 in that the electroniccomponent 32 is covered with a non-magnetic member 50. As thenon-magnetic member 50, a common resin can be used. By interposing thenon-magnetic member 50 between the electronic component 32 and themagnetic mold resin 40, a sufficient distance between the electroniccomponent 32 and magnetic mold resin 40 can be ensured, so that it ispossible to reduce the fluctuation of characteristics such as theinductance value.

The following describes a manufacturing method for the electroniccircuit package 11A according to the present embodiment.

FIGS. 3 to 5 are process views for explaining a manufacturing method forthe electronic circuit package 11A.

As illustrated in FIG. 3, an assembly substrate 20A having a multilayerwiring structure is prepared. A plurality of the land patterns 23 areformed on the front surface 21 of the assembly substrate 20A, and aplurality of the external terminals 26 are formed on the back surface 22of the assembly substrate 20A. Further, a plurality of the internalwirings 25 are formed in an inner layer of the assembly substrate 20A. Adashed line a in FIG. 3 denotes a part to be cut in a subsequent dicingprocess.

Then, as illustrated in FIG. 3, the plurality of electronic components31 and 32 are mounted on the front surface 21 of the assembly substrate20A so as to be connected to the land patterns 23. Specifically, thesolder 24 is provided on the land pattern 23, followed by mounting ofthe electronic components 31 and 32 and by reflowing, whereby theelectronic components 31 and 32 are connected to the land patterns 23.

Then, as illustrated in FIG. 4, the front surface 21 of the assemblysubstrate 20A is covered with the magnetic mold resin 40 so as to embedthe electronic components 31 and 32 in the magnetic mold resin 40.Examples of the formation method for the magnetic mold resin 40 mayinclude transfer molding, compression molding, injection molding, castmolding, vacuum cast molding, dispense molding, and molding using a slitnozzle.

Then, as illustrated in FIG. 5, the assembly substrate 20A is cut alongthe dashed line a to divide the assembly substrate 20A into individualsubstrates 20, whereby the electronic circuit package 11A according tothe present embodiment is completed.

The following describes details of the composite magnetic sealingmaterial constituting the magnetic mold resin 40.

FIG. 6 is a schematic view for explaining a configuration of a compositemagnetic sealing material constituting the magnetic mold resin 40.

As illustrated in FIG. 6, a composite magnetic sealing material 2constituting the magnetic mold resin 40 includes a resin material 4, anda first magnetic filler 5, a second magnetic filler 6 and a non-magneticfiller 8 which are blended in the resin material 4. Although notespecially limited, the resin material 4 is preferably composed mainlyof a thermosetting resin material. Specifically, the resin material 4 ispreferably composed mainly of an epoxy resin, a phenol resin, a urethaneresin, a silicone resin, or an imide resin and more preferably uses abase resin and a curing agent used for an epoxy resin-based or a phenolresin-based semiconductor sealing material.

The most preferable is the epoxy resin having a reactive epoxy group atits terminal, which can be combined with various types of curing agentsand curing accelerators. Examples of the epoxy resin include a bisphenolA epoxy resin, a bisphenol F epoxy resin, a phenoxy type epoxy resin, anaphthalene type epoxy resin, a multifunctional-type epoxy resin(dicyclopentadiene type epoxy resin, etc.), a biphenyl-type(bifunctional) epoxy resin, and an epoxy resin having a specialstructure. Among them, the biphenyl type epoxy resin, naphthalene typeepoxy resin, and dicyclopentadiene type epoxy resin are useful sincethey can attain low thermal expansion. Examples of the curing agent orcuring accelerator include amine-based compound alicyclic diamine,aromatic diamine, other amine-based compounds (imidazole, tertiaryamine, etc.), an acid anhydride compound (high-temperature curing agent,etc.), a phenol resin (novolac type phenol resin, cresol novolac typephenol resin, etc.), an amino resin, dicyandiamide, and a Lewis acidcomplex compound. For material kneading, known means such as a kneader,three-roll mills, or a mixer may be used.

The first magnetic filler 5 is formed of an Fe—Ni based material andcontains 32 wt. % or more and 39 wt. % or less of a metal materialcomposed mainly of Ni. The remaining 61-68 wt. % is Fe. The blendingratio of the first and second magnetic fillers 5 and 6 to the compositemagnetic sealing material 2 is 50 vol. % or more and 85 vol. % or less.When the blending ratio of the first and second magnetic fillers 5 and 6is less than 50 vol. %, it is difficult to obtain sufficient magneticcharacteristics; on the other hand, when the blending ratio of the firstand second magnetic fillers 5 and 6 exceeds 85 vol. %, it is difficultto ensure characteristics, such as flowability, required for a sealingmaterial.

The metal material composed mainly of Ni may contain a small amount ofCo. That is, a part of Ni may be substituted by Co. The containment ofCo enables a further reduction in the thermal expansion coefficient ofthe composite magnetic sealing material 2. The adding amount of Co tothe first magnetic filler 5 is preferably 0.1 wt. % or more and 5 wt. %or less.

The second magnetic filler 6 contains at least one selected from thegroup consisting of Fe, an Fe—Co based alloy, an Fe—Ni based alloy, anFe—Al based alloy, an Fe—Si based alloy, an Ni—Zn based spinel ferrite,an Mn—Zn based spinel ferrite, an Ni—Cu—Zn based spinel ferrite, an Mgbased spinel ferrite, and an yttrium-iron based garnet ferrite. Thesecond magnetic filler 6 may be made of a single material or may be amixed filler obtained by mixing a filler made of a certain material anda filler made of another material.

The first magnetic filler 5 has a larger grain diameter than the secondmagnetic filler 6. More specifically, as illustrated in FIG. 33, thefirst magnetic filler 5 has the grain size distribution denoted by A,whereas the second magnetic filler 6 has the grain size distributiondenoted by B. That is, the second magnetic filler 6 has a smaller grainsize than the first magnetic filler 5. Although not particularlylimited, it is preferable that the median diameter (D50) of the firstmagnetic filler 5 is about 5 μm to about 30 μm and that the mediandiameter (D50) of the second magnetic filler 6 is about 0.01 μm to about5 μm and, it is more preferable that the median diameter (D50) of thefirst magnetic filler 5 is about 5 μm to about 20 μm, and that themedian diameter (D50) of the second magnetic filler 6 is about 0.01 μmto about 3 μm. Such a difference in the grain size distribution allowsthe first and second magnetic fillers 5 and 6 to be closely packed inthe resin material 4. When a mixed filler obtained by mixing a pluralityof different materials is used as the second magnetic filler 6, it isnot essential that the grain size distributions of the respectivefillers match each other. Further, the first and second magnetic fillers5 and 6 may be made of substantially the same material, while the grainsize distribution thereof alone is differentiated.

The shape of each of the first and second magnetic fillers 5 and 6 isnot especially limited. However, the first and second magnetic fillers 5and 6 may each preferably be formed into a spherical shape for closepacking. Further, forming the first and second magnetic fillers 5 and 6into a substantially spherical shape enables a reduction in damage toelectronic components during molding. Particularly, for close packing orclosest packing, each of the first and second magnetic fillers 5 and 6is preferably formed into a true sphere. The first and second magneticfillers 5 and 6 each preferably have a high tap density and a smallspecific surface area. As a formation method for the first and secondmagnetic fillers 5 and 6, there are known a water atomization method, agas atomization method, a centrifugal disc atomization method, a heatingand pressurizing reaction, a thermal decomposition method, aspray-drying method, a compression molding method, and a rollinggranulation method.

Although not especially limited, the surface of the first and secondmagnetic fillers 5 and 6 is covered with an insulating coat 7 formed ofan oxide of metal such as Si, Al, Ti, or Mg or an organic material forenhancement of flowability, adhesion, and insulation performance. Tosufficiently enhance the volume resistivity of the composite magneticsealing material 2, the film thickness of the insulating coat 7 ispreferably set to 10 nm or more. The insulating coat 7 may be achievedby coating a thermosetting material on the surface of the first andsecond magnetic fillers 5 and 6 or may be achieved by formation of anoxide film by hydration of metal alkoxide such as tetraethyloxysilane ortetraemthyloxysilane and, most preferably, it is achieved by formationof a silicon oxide coating film. Further, more preferably,organofunctional coupling treatment is applied to the insulating coat 7.

In this embodiment, the composite magnetic sealing material 2 containsthe non-magnetic filler 8. As the non-magnetic filler 8, a materialhaving a smaller thermal expansion coefficient than that of the firstand second magnetic fillers 5 and 6, such as SiO₂, a low thermalexpansion crystallized glass (lithium aluminosilicate based crystallizedglass), ZrW₂O₂,)(ZrO)₂P₂O₂, KZr₂ (PO₄)₃, or Zr₂(WO₄) (PO₄)₂, or amaterial having a negative thermal expansion coefficient is preferablyused. By adding the non-magnetic filler 8 to the composite magneticsealing material 2, it is possible to further reduce the thermalexpansion coefficient. Further, the following materials may be added tothe composite magnetic sealing material 2: flame retardant such asaluminum oxide or magnesium oxide; carbon black, pigment, or dye forcoloring; surface-treated nanosilica having a particle diameter of 100nm or less for enhancement of slidability, flowability, anddispersibility/kneadability; and a wax component for enhancement of moldreleasability. In the present invention, it is not essential that thecomposite magnetic sealing material constituting the magnetic mold resin40 contains the non-magnetic filler.

Further, organofunctional coupling treatment may be applied to thesurface of the first and second magnetic fillers 5 and 6 or surface ofthe non-magnetic filler 8 for enhancement of adhesion and flowability.The organofunctional coupling treatment may be performed using a knownwet or dry method, or by an integral blend method. Further, the surfaceof the first and second magnetic fillers 5 and 6 or surface of thenon-magnetic filler 8 may be coated with a thermosetting resin forenhancement of wettability.

When the non-magnetic filler 8 is added, the ratio of the amount of thenon-magnetic filler 8 relative to the sum of the amounts of the firstand second magnetic fillers 5 and 6 and the non-magnetic filler 8 ispreferably 1 vol. % or more and 30 vol. % or less. In other words, 1vol. % or more and 30 vol. % or less of the first and second magneticfillers 5 and 6 can be substituted by the non-magnetic filler 8. Whenthe additive amount of the non-magnetic filler 8 is less than 1 vol. %,addition effect of the non-magnetic filler 8 is hardly obtained; on theother hand, when the additive amount of the non-magnetic filler 8exceeds 30 vol. %, the relative amount of the first and second magneticfillers 5 and 6 is too small, resulting in difficulty in providingsufficient magnetic characteristics.

As illustrated in FIG. 33, the non-magnetic filler 8 has the grain sizedistribution denoted by C. In the example of FIG. 33, the grain diameterof the non-magnetic filler 8 is smaller than that of the second magneticfiller 6. Although not particularly limited, the median diameter (D50)of the non-magnetic filler 8 is about 0.01 μm to about 3 μm. When thenon-magnetic filler 8 having a smaller grain diameter than the secondmagnetic filler 6 is used as described above, the second magnetic filler6 can be packed more densely, making it possible to improve the magneticcharacteristics. For further improvement of magnetic characteristics,the non-magnetic filler 8 may not be added, that is, only the first andsecond magnetic fillers 5 and 6 may be added.

However, it is not essential that the grain diameter of the non-magneticfiller 8 is smaller than that of the second magnetic filler 6, but thegrain diameter (denoted by C) of the non-magnetic filler 8 may be largerthan that (denoted by B) of the second magnetic filler 6, as illustratedin FIG. 34. When the non-magnetic filler 8 having a larger graindiameter than the second magnetic filler 6 is used, the non-magneticfiller 8 can be packed more densely, making it possible to furtherreduce the thermal expansion coefficient. Alternatively, the graindiameter of the non-magnetic filler 8 may be equivalent to that of thesecond magnetic filler 6. As the material for the non-magnetic filler 8,a low thermal expansion crystallized glass (lithium aluminosilicatebased crystallized glass) can be used.

The composite magnetic sealing material 2 may be a liquid or solid,depending on selection of a base resin and a curing agent according tothe molding method therefor. The composite magnetic sealing material 2in a solid state may be formed into a tablet shape for transfer moldingand into a granular shape for injection molding or compression molding.The molding method using the composite magnetic sealing material 2 maybe appropriately selected from among the followings: transfer molding;compression molding; injection molding; cast molding; vacuum castmolding; vacuum printing; printing; dispensing; and a method using aslit nozzle. A molding condition may be appropriately selected fromcombinations of the base resin, curing agent and curing accelerator tobe used. Further, after-cure treatment may be applied as needed afterthe molding.

FIG. 7 is a graph illustrating the relationship between the Ni ratio ofthe first magnetic filler 5 and the thermal expansion coefficient andthe magnetic permeability of the composite magnetic sealing material 2.The graph of FIG. 7 represents a case where the first magnetic filler 5is composed of substantially only Fe and Ni. Here, it is assumed thatthe additive amount of the first magnetic filler 5 relative to thecomposite magnetic sealing material 2 is 70 vol. % and the secondmagnetic filler 6 and the non-magnetic filler 8 are not added to thecomposite magnetic sealing material 2.

As illustrated in FIG. 7, when the Ni ratio of the first magnetic filler5 is 32 wt. % or more and 39 wt. % or less, the thermal expansioncoefficient of the composite magnetic sealing material 2 is remarkablyreduced (it may be reduced to 10 ppm/° C. in some conditions). In theexample of FIG. 7, the smallest thermal expansion coefficient (about 9.3ppm/° C.) is obtained when the Ni ratio is about 35 wt. %. On the otherhand, the magnetic permeability is not strongly correlated to the Niratio, and μ is 12 to 13 in the range of the Ni ratio illustrated inFIG. 7.

The reason that such characteristics are obtained is that invarcharacteristics where volumetric changes due to thermal expansion andmagnetic distortion cancel out each other is exhibited when the Ni ratiofalls within the above range. A material where the invar characteristicis exhibited is called an invar material, which is known as a materialfor a die requiring high precision; however, it was not used as amaterial for the magnetic filler to be blended in a composite magneticsealing material. The present inventor pays attention to the magneticcharacteristics and small thermal expansion coefficient that the invarmaterial has and uses the invar material as a material for the magneticfiller and thereby realize the composite magnetic sealing material 2having the magnetic shielding characteristics and a small thermalexpansion coefficient. Moreover, in this embodiment, the magneticshielding characteristics is enhanced by adding not only the firstmagnetic filler 5 of the invar material but also the second magneticfiller 6.

FIG. 8 is a graph illustrating the relationship between the Ni ratio ofthe first magnetic filler 5 and the thermal expansion coefficient of thecomposite magnetic sealing material 2. The graph of FIG. 8 represents acase where the first magnetic filler 5 is composed substantially of onlyFe and Ni. Here, it is assumed that the additive amount of the firstmagnetic filler 5 relative to the composite magnetic sealing material 2is 50 vol. %, 60 vol. %, or 70 vol. % and the second magnetic filler 6and the non-magnetic filler 8 are not added to the composite magneticsealing material 2.

As illustrated in FIG. 8, even in a case where the additive amount ofthe first magnetic filler 5 is either 50 vol. %, 60 vol. %, or 70 vol.%, when the Ni ratio of the first magnetic filler 5 is 32 wt. % or moreand 39 wt. % or less, the thermal expansion coefficient of the compositemagnetic sealing material 2 is remarkably reduced. The more the additiveamount of the first magnetic filler 5 is, the smaller the thermalexpansion coefficient. Therefore, when the additive amount of the firstmagnetic filler 5 is small (e.g., 30 vol. %), the non-magnetic filler 8formed of fused silica is further added to reduce the thermal expansioncoefficient of the composite magnetic sealing material 2 to 15 ppm/° C.or less, for example. Specifically, by setting the total additive amountof the first and second magnetic fillers 5 and 6 and the non-magneticfiller 8 to 50 vol. % or more and 85 vol. % or less, the thermalexpansion coefficient of the composite magnetic sealing material 2 canbe sufficiently reduced (e.g., to 15 ppm/° C. or less).

FIG. 9 is a graph illustrating the relationship between the Ni ratio ofthe first magnetic filler 5 and the magnetic permeability of thecomposite magnetic sealing material 2. As in the case of the graph ofFIG. 8, the graph of FIG. 9 represents a case where the first magneticfiller 5 is composed substantially of only Fe and Ni and the additiveamount of the first magnetic filler 5 relative to the composite magneticsealing material 2 is 50 vol. %, 60 vol. %, or 70 vol. %, and the secondmagnetic filler 6 and the non-magnetic filler 8 are not added to thecomposite magnetic sealing material 2.

As illustrated in FIG. 9, even in a case where the additive amount ofthe first magnetic filler 5 is either 50 vol. %, 60 vol. %, or 70 vol.%, the Ni ratio and the magnetic permeability are not stronglycorrelated to each other. The more the additive amount of the firstmagnetic filler 5 is, the larger the magnetic permeability. The magneticpermeability can be adjusted by an amount of the second magnetic filler6.

FIG. 10 is a graph illustrating the relationship between the Co ratio ofthe first magnetic filler 5 and the thermal expansion coefficient andmagnetic permeability of the composite magnetic sealing material 2. Thegraph of FIG. 10 represents a case where the sum of the amounts of Niand Co contained in the first magnetic filler 5 is 37 wt. %, theadditive amount of the first magnetic filler 5 relative to the compositemagnetic sealing material 2 is 70 vol. %, and the second magnetic filler6 and the non-magnetic filler 8 are not added to the composite magneticsealing material 2.

As illustrated in FIG. 10, as compared to a case where Co is notcontained (Co=0 wt. %) in the first magnetic filler 5, the thermalexpansion coefficient of the composite magnetic sealing material 2 isfurther reduced when Ni constituting the first magnetic filler 5 issubstituted by 8 wt. % or less of Co. The thermal expansion coefficientis markedly reduced when Ni is substituted by 5 wt. % or less of Co.However, when the substituted amount by Co is 10 wt. %, the thermalexpansion coefficient is conversely increased. Therefore, the additiveamount of Co relative to the first magnetic filler 5 is preferably 0.1wt. % or more and 8 wt. % or less, and more preferably 0.1 wt. % or moreand 5 wt. % or less.

FIG. 11 is a graph illustrating the relationship between the additiveratio of the non-magnetic filler 8 and the thermal expansion coefficientof the composite magnetic sealing material 2. The graph of FIG. 11represents a case where the sum of the amounts of the first magneticfiller 5 and the non-magnetic filler 8 is 70 vol. %, the first magneticfiller 5 is composed of 64 wt. % of Fe and 36 wt. % of Ni, and thenon-magnetic filler 8 is formed of SiO₂. The second magnetic filler 6 isnot added.

As illustrated in FIG. 11, as the ratio of the amount of thenon-magnetic filler 8 is increased, the thermal expansion coefficient isreduced. However, when the ratio of the amount of the non-magneticfiller 8 relative to 70 vol. % of the first magnetic filler 5 exceeds 30vol. %, a thermal expansion coefficient reduction effect is reduced, andwhen the ratio of the amount of the non-magnetic filler 8 relative to 60vol. % of the first magnetic filler 5 exceeds 40 vol. %, the thermalexpansion coefficient reduction effect is nearly saturated. Thus, theamount of the non-magnetic filler 8 relative to the sum of the amountsof the first and second magnetic fillers 5 and 6 and non-magnetic filler8 is preferably 1 vol. % or more and 40 vol. % or less and, morepreferably, 1 vol. % or more and 30 vol. % or less.

FIG. 12 is a graph illustrating the relationship between thepresence/absence of the insulating coat 7 formed on the surface of thefirst magnetic filler 5 and volume resistivity. Two compositions areprepared as a material for the first magnetic filler 5 as follows:composition A (Fe=64 wt. %, Ni=36 wt. %); and composition B (Fe=63 wt.%, Ni=32 wt. %, Co=5 wt. %). The insulating coat 7 is formed of SiO₂having a thickness of 40 nm. The first magnetic filler 5 of either thecomposition A or composition B has a cut diameter of 32 μm and aparticle diameter D50 of 20 μm.

As illustrated in FIG. 12, in both the composition A and composition B,coating with the insulating coat 7 significantly increases the volumeresistivity of the first magnetic filler 5. In addition, the coatingwith the insulating coat 7 reduces pressure dependency of the firstmagnetic filler 5 at the time of measurement. The same is true on thesecond magnetic filler 6, coating with the insulating coat 7significantly increases the volume resistivity of the second magneticfiller 6.

FIG. 13 is a graph illustrating the relationship between the filmthickness of the insulating coat 7 formed on the surface of the firstmagnetic filler 5 and volume resistivity. The graph of FIG. 13represents a case where the first magnetic filler 5 is composed of 64wt. % of Fe and 36 wt. % of Ni. The particle diameter of the firstmagnetic filler 5 is equal to the particle diameter of the firstmagnetic filler 5 in the example of FIG. 12.

As illustrated in FIG. 13, by coating the first magnetic filler 5 withthe insulating coat 7 having a film thickness of 10 nm or more, thevolume resistivity of the first magnetic filler 5 is increased. Inparticular, when the first magnetic filler 5 is coated with theinsulating coat 7 having a film thickness of 30 nm or more, a very highvolume resistivity can be obtained regardless of an applied pressure atthe time of measurement. The same is true on the second magnetic filler6, coating with the insulating coat 7 having a film thickness of 10 nmor more significantly increases the volume resistivity of the secondmagnetic filler 6.

FIG. 14 is a graph illustrating the relationship between the volumeresistivity of the first magnetic filler 5 and that of the compositemagnetic sealing material 2.

As illustrated in FIG. 14, the volume resistivity of the first magneticfiller 5 and that of the composite magnetic sealing material 2 are inproportion to each other. In particular, when the volume resistivity ofthe first magnetic filler 5 is 10⁵Ωcm or more, the volume resistivity ofthe composite magnetic sealing material 2 can be increased to 10¹⁰ Ωcmor more. The same is true on the second magnetic filler 6, when thevolume resistivity of the second magnetic filler 6 is 10⁵Ωcm or more,the volume resistivity of the composite magnetic sealing material 2 canbe increased to 10¹⁰Ωcm or more. When the composite magnetic sealingmaterial 2 having a volume resistivity of 10¹⁰ Ωcm or more is used as amolding material for electronic circuit package, a sufficient insulatingperformance can be ensured.

As described above, the electronic circuit packages 11A and 11B eachhave the magnetic mold resin 40 composed of composite magnetic sealingmaterial 2 having very small thermal expansion coefficient. Therefore,it is possible to prevent the warp of the substrate, interfacialdelamination or crack of a molding material caused due to a temperaturechange with obtaining the magnetic shielding characteristics.

Second Embodiment

FIG. 15 is a cross-sectional view illustrating a configuration of anelectronic circuit package 12A according to the second embodiment of thepresent invention.

As illustrated in FIG. 15, an electronic circuit package 12A accordingto the present embodiment differs from the electronic circuit package11A according to the first embodiment illustrated in FIG. 1 in that aplanar size of the magnetic mold resin 40 is slightly smaller than aplanar size of the substrate 20 and, therefore, an outer peripheralportion of the front surface 21 of the substrate 20 is exposed from themagnetic mold resin 40. Other configurations are the same as those ofthe electronic circuit package 11A according to the first embodiment.Thus, in FIG. 15, the same reference numerals are given to the sameelements as in FIG. 1, and repetitive descriptions will be omitted.

As exemplified by the electronic circuit package 12A according to thepresent embodiment, it is not essential in the present invention thatthe side surface 42 of the magnetic mold resin 40 and the side surface27 of the substrate 20 form the same plane, but the planar size of themagnetic mold resin 40 may be smaller than that of the substrate 20.

FIGS. 16 to 18 are views for explaining a manufacturing method for theelectronic circuit package 12A.

First, as illustrated in FIG. 16, the substrate 20 is prepared bypreviously cutting the assembly substrate 20A into individual pieces,and the plurality of electronic components 31 and 32 are mounted on thesubstrate 20 so as to be connected to the land patterns 23 on the frontsurface 21 of the substrate 20. Specifically, the solder 24 is providedon the land patterns 23, followed by mounting of the electroniccomponents 31 and 32 and by reflowing, whereby the electronic components31 and 32 are connected to the land pattern 23.

Then, as illustrated in FIG. 17, the substrate 20 on which theelectronic components 31 and 32 are mounted is set in a mold 80. Then,as illustrated in FIG. 18, a composite magnetic material which is amaterial forming the magnetic mold resin 40 is injected along a flowpath 81 of the mold 80, followed by pressuring and heating. Theelectronic circuit package 12A according to the present embodiment isthen completed.

As described above, the magnetic mold resin 40 may be formed afterdividing the assembly substrate 20A into individual substrates 20.

Third Embodiment

FIG. 19 is a cross-sectional view illustrating a configuration of anelectronic circuit package 13A according to the third embodiment of thepresent invention.

As illustrated in FIG. 19, the electronic circuit package 13A accordingto the present embodiment differs from the electronic circuit package11A in that it further includes a metal film 60 that covers an uppersurface 41 and a side surface 42 of the magnetic mold resin 40 andcovers a side surface 27 of the substrate 20. Out of the internalwirings 25 illustrated in FIG. 19, internal wirings 25G are power supplypatterns. A part of the power supply patterns 25G is exposed from thesubstrate 20 on the side surface 27. The power supply patterns 25G aretypically ground patterns to which a ground potential is to be applied;however, it is not limited to the ground patterns as long as the powersupply patterns 25G are a pattern to which a fixed potential is to beapplied. Other configurations are the same as those of the electroniccircuit package 11A according to the first embodiment. Thus, in FIG. 19,the same reference numerals are given to the same elements as in FIG. 1,and repetitive descriptions will be omitted.

The metal film 60 serves as an electromagnetic shielding and ispreferably mainly composed of at least one metal selected from a groupconsisting of Au, Ag, Cu, and Al. The metal film 60 preferably has aresistance as low as possible and most preferably uses Cu in terms ofcost. An outer surface of the metal film 60 is preferably covered withan anticorrosive metal such as SUS, Ni, Cr, Ti, or brass or anantioxidant film made of a resin such as an epoxy resin, a phenol resin,an imide resin, an urethane resin, or a silicone resin. The reason forthis is that the metal film 60 undergoes oxidative deterioration by anexternal environment such as heat or humidity; and, therefore, theaforementioned treatment is preferable to suppress and prevent theoxidative deterioration. A formation method for the metal film 60 may beappropriately selected from known methods, such as a sputtering method,a vapor-deposition method, an electroless plating method, anelectrolytic plating method. Before formation of the metal film 60,pretreatment for enhancing adhesion, such as plasma treatment, couplingtreatment, blast treatment, or etching treatment, may be performed. As abase of the metal film 60, a high adhesion metal film such as a titaniumfilm, a chromium film, or an SUS film may be formed thinly in advance.

As illustrated in FIG. 19, the power supply patterns 25G are exposed tothe side surfaces 27 of the substrate 20. The metal film 60 covers theside surfaces 27 of the substrate 20 and is thereby connected to thepower supply pattern 25G.

It is desirable that a resistance value at an interface between themetal film 60 and the magnetic mold resin 40 is equal to or larger than10⁶Ω. In this case, an eddy current generated when electromagnetic wavenoise enters the metal film 60 hardly flows in the magnetic mold resin40, which can prevent deterioration in the magnetic characteristics ofthe magnetic mold resin 40 due to inflow of the eddy current. Theresistance value at the interface between the metal film 60 and themagnetic mold resin 40 refers to a surface resistance of the magneticmold resin 40 when the metal film 60 and magnetic mold resin 40 directlycontact each other and to a surface resistance of an insulating filmwhen the insulating film is present between the metal film 60 and themagnetic mold resin 40. The resistance value at the interface betweenthe metal film 60 and the magnetic mold resin 40 is preferably equal toor larger than 10⁶Ω over the entire area of the interface; however, itdoes not matter if the resistance value is partly smaller than 10⁶Ω.

Basically, the surface resistance value of the magnetic mold resin 40substantially coincides with the volume resistivity of the magnetic moldresin 40. Thus, basically, when the volume resistivity of the magneticmold resin 40 is equal to or larger than 10¹⁰Ωcm, the surface resistancevalue of the magnetic mold resin 40 is also equal to or larger than10¹⁰Ω. However, as explained with reference to FIG. 5, the magnetic moldresin 40 undergoes dicing at manufacturing, so that the first and secondmagnetic fillers 5 and 6 may be exposed to a cut surface (i.e., sidesurface 42), and in this case, the surface resistance value of the sidesurface 42 becomes smaller than the volume resistivity. Similarly, whenthe top surface 41 of the magnetic mold resin 40 is ground for reducingheight or roughing the surface, the first and second magnetic fillers 5and 6 may be exposed to the top surface 41, and in this case, thesurface resistance value of the top surface 41 becomes smaller than thevolume resistivity. As a result, even when the volume resistivity of themagnetic mold resin 40 is equal to or larger than 10¹⁰ Ωcm, the surfaceresistance value of the magnetic mold resin 40 may be smaller than10¹⁰Ω; however, in such a case, when the surface resistance value of themagnetic mold resin 40 is equal to or larger than 10⁶Ω, it is possibleto prevent inflow of the eddy current.

When the surface resistance value of the top surface 41 or side surface42 of the magnetic mold resin 40 is reduced to smaller than 10⁶Ω, a thininsulating material may be formed on the top surface 41 or side surface42 of the magnetic mold resin 40. FIG. 20 is a cross-sectional viewillustrating a configuration of an electronic circuit package 13Baccording to a first modification. The electronic circuit package 13B ofFIG. 20 differs from the electronic circuit package 13A of FIG. 19 inthat a thin insulating film 70 is interposed between the top surface 41and side surfaces 42 of the magnetic mold resin 40 and the metal film60. With this configuration, even when the surface resistance value ofthe top surface 41 or side surface 42 of the magnetic mold resin 40 isreduced to smaller than 10⁶Ω, the resistance value at the interfacebetween the metal film 60 and the magnetic mold resin 40 can be madeequal to or larger than 10⁶Ω, making it possible to preventdeterioration in the magnetic characteristics due to the eddy current.

FIG. 21 is a cross-sectional view illustrating a configuration of anelectronic circuit package 13C according to a second modification of thethird embodiment.

As illustrated in FIG. 21, an electronic circuit package 13C accordingto the second modification differs from the electronic circuit package13A illustrated in FIG. 19 in that a planar size of the magnetic moldresin 40 is slightly smaller than a planar size of the substrate 20 and,therefore, an outer peripheral portion of the front surface 21 of thesubstrate is exposed from the magnetic mold resin 40. Otherconfigurations are the same as those of the electronic circuit package13A. Thus, in FIG. 21, the same reference numerals are given to the sameelements as in FIG. 19, and repetitive descriptions will be omitted.

As exemplified by the electronic circuit package 13C according to thesecond modification, it is not essential in the present invention thatthe side surface 42 of the magnetic mold resin 40 and the side surface27 of the substrate 20 form the same plane, but the planar size of themagnetic mold resin 40 may be smaller than that of the substrate 20.

Further, as illustrated in FIG. 22 which illustrates an electroniccircuit package 13D as the third modification of this embodiment, astructure in which the metal film 60 does not cover the side surface 27of the substrate 20 may be employed. In this case, a power supplypatterns 28G are provided at an outer peripheral portion of the surface21 of the substrate 20 that is exposed from the magnetic mold resin 40and contacts the metal film 60. As a result, a fixed potential such as aground potential is applied to the metal film 60.

FIG. 23 is a cross-sectional view illustrating a configuration of anelectronic circuit package 13E according to the fourth modification ofthe third embodiment.

As illustrated in FIG. 23, an electronic circuit package 13E accordingto the fourth modification differs from the electronic circuit package13A illustrated in FIG. 19 in that the planar size of the magnetic moldresin 40 is slightly larger than the planar size of the substrate 20.Other configurations are the same as those of the electronic circuitpackage 13A. Thus, in FIG. 23, the same reference numerals are given tothe same elements as in FIG. 19, and repetitive descriptions will beomitted.

As exemplified by the electronic circuit package 13E according to thefourth modification, in the present invention, the planar size of themagnetic mold resin 40 may be larger than that of the substrate 20.

As described above, the electronic circuit packages 13A to 13E accordingto the present embodiment use the magnetic mold resin 40 and have thesurfaces covered with the metal film 60. With this configuration, it ispossible to obtain a composite shielding structure. This can effectivelyshield electromagnetic wave noise radiated from the electroniccomponents 31 and 32 and external electromagnetic wave noise enteringthe electronic components 31 and 32 while achieving reduction in height.In particular, the electronic circuit packages 13A to 13E according tothe present embodiment can shield the electromagnetic wave noiseradiated from the electronic components 31 and 32 more effectively. Thisis because the electromagnetic wave noise radiated from the electroniccomponents 31 and 32 is partly absorbed when it passes through themagnetic mold resin 40, and the remaining electromagnetic wave noisethat has not been absorbed is reflected by the metal film 60 and passesthrough the magnetic mold resin 40 once again. As described above, themagnetic mold resin 40 acts on the incident electromagnetic wave noisetwice, thereby effectively shielding the electromagnetic wave noiseradiated from the electronic components 31 and 32.

Further, when the volume resistivity of the magnetic mold resin 40 isequal to or more than 10¹⁰ Ωcm in the electronic circuit packages 13A to13E according to the present embodiment, it is possible to ensuresufficient insulating performance required for the mold member. Inaddition, when the resistance value at the interface between themagnetic mold resin 40 and the metal film 60 is equal to or more than10⁶Ω, it is possible to substantially prevent the eddy current generatedwhen the electromagnetic wave noise enters the metal film 60 fromflowing into the magnetic mold resin 40. As a result, it is possible toprevent deterioration in the magnetic characteristics of the magneticmold resin 40 due to inflow of the eddy current.

FIG. 24 is a graph illustrating noise attenuation in the electroniccircuit package 13A in the case where the substrate 20 has a thicknessof 0.25 mm, and the magnetic mold resin 40 has a thickness of 0.50 mm.The metal film 60 is composed of a laminated film of Cu and Ni, and twotypes of metal films 60 whose Cu films have different thicknesses areevaluated. Specifically, the metal film 60 of sample A has aconfiguration in which the Cu film having a thickness of 4 μm and the Nifilm having a thickness of 2 μm are laminated, and the metal film 60 ofsample B has a configuration in which the Cu film having a thickness of7 μm and the Ni film having a thickness of 2 μm are laminated. Forcomparison, values of samples C and D each formed by using a moldingmaterial not containing the first and second magnetic fillers 5 and 6are also shown. The metal film 60 of sample C has a configuration inwhich the Cu film having a thickness of 4 μm and the Ni film having athickness of 2 μm are laminated, and the metal film 60 of sample D has aconfiguration in which the Cu film having a thickness of 7 μm and the Nifilm having a thickness of 2 μm are laminated.

As illustrated in FIG. 24, when the composite magnetic sealing material2 containing the first and second magnetic fillers 5 and 6 is used,noise attenuation effect is enhanced especially at a frequency band of100 MHz or less as compared to a case where the molding material notcontaining the first and second magnetic fillers 5 and 6 is used.Further, it can be seen that the larger the thickness of the metal film60, the higher the noise attenuation performance.

FIGS. 25 to 27 are graphs each illustrating the relationship between thefilm thickness of the metal film 60 included in the electronic circuitpackage 13A and noise attenuation. FIG. 25, FIG. 26, and FIG. 27illustrate the noise attenuation in the frequency bands of 20 MHz, 50MHz, and 100 MHz, respectively. For comparison, a value obtained when amolding material not containing the first and second magnetic fillers 5and 6 is also shown.

As illustrated, in all the frequency bands of FIGS. 25 to 27, the largerthe thickness of the metal film 60, the higher the noise attenuationperformance. Further, by using the composite magnetic sealing material 2containing the first and second magnetic fillers 5 and 6, it is possibleto obtain higher noise attenuation performance in all the frequencybands of FIGS. 25 to 27, than in a case where a molding material notcontaining the first and second magnetic fillers 5 and 6.

FIG. 28 is a graph illustrating the warp amount of the substrate 20during temperature rising and that during temperature dropping in theelectronic circuit packages 11A (without metal film) and the electroniccircuit packages 13A (with metal film). For comparison, values obtainedwhen the first and second magnetic fillers 5 and 6 are substituted bythe non-magnetic filler formed of SiO₂ are shown in FIG. 29.

As illustrated in FIG. 28, the warp amount of the substrate 20 causeddue to a temperature change is smaller in the electronic circuit package13A having the metal film 60 than in the electronic circuit package 11Anot having the metal film 60. Further, as is clear from a comparisonbetween FIGS. 28 and 29, the warp characteristics of the respectiveelectronic circuit packages 11A and 13A using the composite magneticsealing material 2 containing the first and second magnetic fillers 5and 6 are substantially equivalent to the warp characteristics of therespective electronic circuit packages 11A and 13A using a moldingmaterial containing the non-magnetic filler formed of SiO₂.

Fourth Embodiment

FIG. 30 is a cross-sectional view illustrating a configuration of anelectronic circuit package 14A according to the fourth embodiment of thepresent invention.

As illustrated in FIG. 30, an electronic circuit package 14A accordingto the present embodiment is the same as the electronic circuit package13A according to the third embodiment illustrated in FIG. 19 except forshapes of the substrate 20 and metal film 60. Thus, in FIG. 30, the samereference numerals are given to the same elements as in FIG. 19, andrepetitive descriptions will be omitted.

In the present embodiment, the side surface 27 of the substrate 20 isformed stepwise. Specifically, a side surface lower portion 27 bprotrudes from aside surface upper portion 27 a. The metal film 60 isnot formed over the entire side surface of the substrate 20 but formedso as to cover the side surface upper portion 27 a and a step portion 27c. That is, the side surface lower portion 27 b is not covered with themetal film 60. Also in the present embodiment, the power supply patterns25G are exposed from the side surface upper portion 27 a of thesubstrate 20, so that the metal film 60 is connected to the power supplypatterns 25G at the exposed portion.

FIGS. 31 and 32 are process views for explaining a manufacturing methodfor the electronic circuit package 14A.

First, the magnetic mold resin 40 is formed on the front surface 21 ofthe assembly substrate 20A by using the method described in FIGS. 3 and4. Then, as illustrated in FIG. 31, a groove 43 is formed along thedashed line a denoting the dicing position. In the present embodiment,the power supply patterns 25G pass the dashed line a as a dicingposition. Thus, when the assembly substrate 20A is cut along the dashedline a, the power supply patterns 25G are exposed from the side surface27 of the substrate 20. The groove 43 is formed so as to completely cutthe magnetic mold resin 40 and so as not to completely cut the assemblysubstrate 20A. As a result, the side surface 42 of the magnetic moldresin 40 and side surface upper portion 27 a and step portion 27 c ofthe substrate 20 are exposed inside the groove 43. A depth of the groove43 is set so as to allow at least the power supply patterns 25G to beexposed from the side surface upper portion 27 a.

Then, as illustrated in FIG. 32, the metal film 60 is formed by using asputtering method, a vapor-deposition method, an electroless platingmethod, an electrolytic plating method, or the like. As a result, thetop surface 41 of the magnetic mold resin 40 and inside of the groove 43are covered with the metal film 60. At this time, the power supplypatterns 25G exposed to the side surface upper portion 27 a of thesubstrate 20 are connected to the metal film 60.

Then, the assembly substrate 20A is cut along the dashed line a todivide the assembly substrate 20A into individual substrates 20, wherebythe electronic circuit package 14A according to the present embodimentis completed.

As described above, according to the manufacturing method for theelectronic circuit package 14A of the present embodiment, formation ofthe groove 43 allows the metal film 60 to be formed before dividing theassembly substrate 20A into individual substrates 20, thereby formingthe metal film 60 easily and reliably.

Fifth Embodiment

FIG. 35 is a cross-sectional view illustrating the configuration of anelectronic circuit package 15A according to a fifth embodiment of thepresent invention.

As illustrated in FIG. 35, the electronic circuit package 15A accordingto the present embodiment differs from the electronic circuit package13A according to the third embodiment illustrated in FIG. 19 in that ithas a soft magnetic metal film 90. Other configurations are the same asthose of the electronic circuit package 13A according to the thirdembodiment, so the same reference numerals are given to the sameelements, and overlapping description will be omitted.

The soft magnetic metal film 90 may be made of Fe or an Fe—Ni basedalloy and functions as both an electromagnetic shield and a secondmagnetic shield. That is, the electronic circuit package 15A accordingto the present embodiment uses the magnetic mold resin 40, and thesurface of the magnetic mold resin 40 is covered with the soft magneticmetal film 90, thus obtaining a double composite shield structure. Theoutside surface of the soft magnetic metal film 90 is preferably coveredwith an antioxidant film made of anticorrosive metal such as SUS, Ni,Cr, Ti, or brass, or resin such as an epoxy resin, a phenol resin, animide resin, an urethane resin, or a silicone resin. This is becauseformation of the anticorrosive film can suppress or prevent oxidationdegradation of the soft magnetic metal film 90 due to externalenvironment such as heat or humidity. The formation method for the softmagnetic metal film 90 may be selected appropriately from known methodssuch as a sputtering method, a vapor-deposition method, an electrolessplating method, and an electrolytic plating method. Before the formationof the soft magnetic metal film 90, adhesion improvement pre-treatmentsuch as plasma treatment, coupling treatment, blast treatment or etchingtreatment may be applied. Further, a high adhesion metal film such astitanium, chrome, or SUS may previously be formed thinly as a base ofthe soft magnetic metal film 90.

As illustrated in FIG. 35, the power supply pattern 25G is exposed tothe side surface 27 of the substrate 20, and the soft magnetic metalfilm 90 covers the side surface 27 of the substrate 20 to be connectedto the power supply pattern 25G.

FIG. 36 is a cross-sectional view illustrating the configuration of anelectronic circuit package 15B according to the first modification ofthe fifth embodiment.

The electronic circuit package 15B according to the modification differsfrom the electronic circuit package 15A illustrated in FIG. 35 in that athin insulating film 70 is interposed between the upper and sidesurfaces 41 and 42 of the magnetic mold resin 40 and the soft magneticmetal film 90. By interposing the insulating film 70, it is possible toprevent deterioration in magnetic characteristics due to an eddy currentloss.

Sixth Embodiment

FIG. 37 is a cross-sectional view illustrating the configuration of anelectronic circuit package 16A according to a sixth embodiment of thepresent invention.

As illustrated in FIG. 37, the electronic circuit package 16A accordingto the present embodiment differs from the electronic circuit package13A according to the third embodiment illustrated in FIG. 19 in that thesoft magnetic metal film 90 is additionally provided between the uppersurface 41 of the magnetic mold resin 40 and the metal film 60. Otherconfigurations are the same as those of the electronic circuit package13A according to the third embodiment, so the same reference numeralsare given to the same elements, and overlapping description will beomitted.

The electronic circuit package 16A according to the present embodimentuses the magnetic mold resin 40, and the surface of the magnetic moldresin 40 is covered with a laminated structure of the soft magneticmetal film 90 and metal film 60, thus obtaining a triple compositeshield structure.

FIG. 38 is a cross-sectional view illustrating the configuration of anelectronic circuit package 16B according to the modification of thesixth embodiment.

The electronic circuit package 16B according to the modification of thesixth embodiment differs from the electronic circuit package 16Aillustrated in FIG. 37 in that the soft magnetic metal film 90 is alsoadditionally provided between the side surface 42 of the magnetic moldresin 40 and the metal film 60. Other configurations are the same asthose of the electronic circuit package 16A illustrated in FIG. 37, sothe same reference numerals are given to the same elements, andoverlapping description will be omitted.

The electronic circuit package 16B has a triple composite shieldstructure in the side surface direction thereof as well, thus making itpossible to obtain a higher shield effect.

Seventh Embodiment

FIG. 39 is a cross-sectional view illustrating the configuration of anelectronic circuit package 17A according to a seventh embodiment of thepresent invention.

As illustrated in FIG. 39, the electronic circuit package 17A accordingto the present embodiment differs from the electronic circuit package13A according to the third embodiment illustrated in FIG. 19 in that thesoft magnetic metal film 90 is formed on an upper surface 61 of themetal film 60. Other configurations are the same as those of theelectronic circuit package 13A according to the third embodiment, so thesame reference numerals are given to the same elements, and overlappingdescription will be omitted.

In the electronic circuit package 17A according to the presentembodiment, the upper surface 41 of the magnetic mold resin 40 iscovered with a laminated structure of the metal film 60 and softmagnetic metal film 90, thus obtaining a triple composite shieldstructure.

FIG. 40 is a cross-sectional view illustrating the configuration of anelectronic circuit package 17B according to the modification of theseventh embodiment.

The electronic circuit package 17B according to the modification of theseventh embodiment differs from the electronic circuit package 17Aillustrated in FIG. 39 in that the soft magnetic metal film 90 furthercovers a side surface 62 of the metal film 60. Other configurations arethe same as those of the electronic circuit package 17A illustrated inFIG. 39, so the same reference numerals are given to the same elements,and overlapping description will be omitted.

The electronic circuit package 17B has a triple composite shieldstructure in the side surface direction thereof as well, thus making itpossible to obtain a higher shield effect.

Eighth Embodiment

FIG. 41 is a cross-sectional view illustrating the configuration of anelectronic circuit package 18A according to an eighth embodiment of thepresent invention.

As illustrated in FIG. 41, the electronic circuit package 18A accordingto the present embodiment differs from the electronic circuit package15A according to the fifth embodiment illustrated in FIG. 35 in that thesoft magnetic metal film 90 is formed only on the upper surface 41 ofthe magnetic mold resin 40 and does not cover the side surface 42 of themagnetic mold resin 40 and the side surface 27 of the substrate 20.Other configurations are the same as those of the electronic circuitpackage 15A according to the fifth embodiment, so the same referencenumerals are given to the same elements, and overlapping descriptionwill be omitted.

In the electronic circuit package 18A according to the presentembodiment, a double composite shield structure can be obtained by themagnetic mold resin 40 and soft magnetic metal film 90. Further, thesoft magnetic metal film 90 is not connected to the power supply pattern25G, thereby simplifying the production process.

While the preferred embodiments of the present invention have beendescribed, the present invention is not limited thereto. Thus, variousmodifications may be made without departing from the gist of theinvention, and all of the modifications thereof are included in thescope of the present invention.

What is claimed is:
 1. A composite magnetic sealing material comprising:a resin material; and a filler blended in the resin material, whereinthe filler includes: a first magnetic filler containing Fe and 32 wt. %or more and 39 wt. % or less of a metal material composed mainly of Ni,the first magnetic filler having a first grain size distribution; asecond magnetic filler having a second grain size distribution smallerthan the first grain size distribution; and a non-magnetic filler. 2.The composite magnetic sealing material as claimed in claim 1, whereinthe metal material further contains 0.1 wt. % or more and 5 wt. % orless of Co relative to a total weight of the first magnetic filler. 3.The composite magnetic sealing material as claimed in claim 1, whereinthe second magnetic filler contains at least one selected from a groupconsisting of Fe, an Fe—Co based alloy, an Fe—Ni based alloy, an Fe—Albased alloy, an Fe—Si based alloy, an Ni—Zn based spinel ferrite, anMn—Zn based spinel ferrite, an Ni—Cu—Zn based spinel ferrite, an Mgbased spinel ferrite, and an yttrium-iron based garnet ferrite.
 4. Thecomposite magnetic sealing material as claimed in claim 1, wherein thesecond magnetic filler has substantially a same composition as that ofthe first magnetic filler.
 5. The composite magnetic sealing material asclaimed in claim 1, wherein a ratio of an amount of the non-magneticfiller relative to a sum of an amounts of the first and second magneticfillers and the non-magnetic filler is 1 vol. % or more and 30 vol. % orless.
 6. The composite magnetic sealing material as claimed in claim 5,wherein the non-magnetic filler contains at least one material selectedfrom a group consisting of SiO2, a low thermal expansion crystallizedglass (lithium aluminosilicate based crystallized glass), ZrW2O8,(ZrO)2P2O7, KZr2(PO4)3, or Zr2(WO4) (PO4)2.
 7. The composite magneticsealing material as claimed in claim 1, wherein the first and secondmagnetic fillers have a substantially spherical shape.
 8. The compositemagnetic sealing material as claimed in claim 1, wherein the first andsecond magnetic fillers are coated with an insulating material.
 9. Thecomposite magnetic sealing material as claimed in claim 8, wherein afilm thickness of the insulating material is 10 nm or more.
 10. Thecomposite magnetic sealing material as claimed in claim 1, wherein theresin material comprises a thermosetting resin material.
 11. Thecomposite magnetic sealing material as claimed in claim 10, wherein thethermosetting resin material contains at least one material selectedfrom a group consisting of an epoxy resin, a phenol resin, a urethaneresin, a silicone resin, or an imide resin.
 12. The composite magneticsealing material as claimed in claim 1, wherein a volume resistivity ofthe composite magnetic sealing material is 1010 □ cm or more.
 13. Anelectronic circuit package comprising: a substrate; an electroniccomponent mounted on a surface of the substrate; and a magnetic moldresin covering the surface of the substrate so as to embed therein theelectronic component, wherein the magnetic mold resin comprising: aresin material; and a filler blended in the resin material, and whereinthe filler includes: a first magnetic filler containing Fe and 32 wt. %or more and 39 wt. % or less of a metal material composed mainly of Ni,the first magnetic filler having a first grain size distribution; asecond magnetic filler having a second grain size distribution smallerthan the first grain size distribution; and a non-magnetic filler. 14.The electronic circuit package as claimed in claim 13, wherein a surfaceresistance value of the magnetic mold resin is 106 □ or more.
 15. Theelectronic circuit package as claimed in claim 13, further comprising ametal film covering the magnetic mold resin, wherein the metal film isconnected to a power supply pattern provided in the substrate.
 16. Theelectronic circuit package as claimed in claim 15, wherein the metalfilm is mainly composed of at least one metal selected from a groupconsisting of Au, Ag, Cu, and Al.
 17. The electronic circuit package asclaimed in claim 15, wherein a surface of the metal film is covered withan antioxidant film.
 18. The electronic circuit package as claimed inclaim 15, further comprising a soft magnetic metal film that covers themagnetic mold resin.
 19. The electronic circuit package as claimed inclaim 13, further comprising a soft magnetic metal film that covers themagnetic mold resin, wherein the soft magnetic metal film is connectedto a power supply pattern provided in the substrate.
 20. The electroniccircuit package as claimed in claim 19, wherein the soft magnetic metalfilm comprises Fe or Fe—Ni based alloy.
 21. The electronic circuitpackage as claimed in claim 19, wherein a surface of the soft magneticmetal film is covered with an antioxidant film.